Historically, telecommunications have involved the transmission of voice and fax signals over a network dedicated to telecommunications, such as the Public Switch Exchange (PBX). Similarly, data communications between computers have been historically transmitted on a dedicated data network, such as a Local Area Network (LAN) or a Wide Area Network (WAN). Currently telecommunications and data transmissions are being merged into an integrated communication network using technology such as Voice over Internet Protocol (VoIP). As new technologies emerge that take advantage of the capabilities of this integrated communication network so do the protocols that enable these technologies.
Two such protocols used in facilitating communications between endpoints are the session initiation protocol (SIP) and the H.323 protocol. However, these protocols were developed independently of each other and the way they negotiate media differs in ways that can make interoperability difficult. For example, it may be the case that one feature of one protocol does not have a corresponding feature in the other protocol. Furthermore, differences in the timing and content of information flow in each protocol are such that there does not exist a simple common scheme to map the information flows to each other. For example, when building a SIP to H.323 protocol gateway one particular problem for the gateway is interoperating a SIP delayed offer INVITE to an H.323 non-fast-start flow. This presents a problem because both endpoints are waiting for the other endpoint to transmit its capabilities, causing a deadlock in which neither endpoint does anything.